/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
 */
package com.opensource.dbhelp.dbutils;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

/**
 * Creates proxy implementations of JDBC interfaces. This avoids incompatibilities between the JDBC 2 and JDBC 3 interfaces. This class is thread safe.
 *
 * @see java.lang.reflect.Proxy
 * @see java.lang.reflect.InvocationHandler
 */
public class ProxyFactory {

	/**
	 * The Singleton instance of this class.
	 */
	private static final ProxyFactory instance = new ProxyFactory();

	/**
	 * Returns the Singleton instance of this class.
	 *
	 * @return singleton instance
	 */
	public static ProxyFactory instance() {
		return instance;
	}

	/**
	 * Protected constructor for ProxyFactory subclasses to use.
	 */
	protected ProxyFactory() {
		super();
	}

	/**
	 * Convenience method to generate a single-interface proxy using the handler's classloader
	 *
	 * @param <T>
	 *            The type of object to proxy
	 * @param type
	 *            The type of object to proxy
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied object
	 */
	public <T> T newProxyInstance(Class<T> type, InvocationHandler handler) {
		return type.cast(Proxy.newProxyInstance(handler.getClass().getClassLoader(), new Class<?>[] { type }, handler));
	}

	/**
	 * Creates a new proxy <code>CallableStatement</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied CallableStatement
	 */
	public CallableStatement createCallableStatement(InvocationHandler handler) {
		return newProxyInstance(CallableStatement.class, handler);
	}

	/**
	 * Creates a new proxy <code>Connection</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied Connection
	 */
	public Connection createConnection(InvocationHandler handler) {
		return newProxyInstance(Connection.class, handler);
	}

	/**
	 * Creates a new proxy <code>Driver</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied Driver
	 */
	public Driver createDriver(InvocationHandler handler) {
		return newProxyInstance(Driver.class, handler);
	}

	/**
	 * Creates a new proxy <code>PreparedStatement</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied PreparedStatement
	 */
	public PreparedStatement createPreparedStatement(InvocationHandler handler) {
		return newProxyInstance(PreparedStatement.class, handler);
	}

	/**
	 * Creates a new proxy <code>ResultSet</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied ResultSet
	 */
	public ResultSet createResultSet(InvocationHandler handler) {
		return newProxyInstance(ResultSet.class, handler);
	}

	/**
	 * Creates a new proxy <code>ResultSetMetaData</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied ResultSetMetaData
	 */
	public ResultSetMetaData createResultSetMetaData(InvocationHandler handler) {
		return newProxyInstance(ResultSetMetaData.class, handler);
	}

	/**
	 * Creates a new proxy <code>Statement</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied Statement
	 */
	public Statement createStatement(InvocationHandler handler) {
		return newProxyInstance(Statement.class, handler);
	}

}